This project is concerned with investigating (1) the structural specializations underlying aqueous humor production in the ciliary epithelium; (2) the anatomical devices which control aqueous humor outflow at the sclero-corneal angle; (3) the morphological basis of the blood-aqueous barrier, (4) and its experimental manipulation with paracentesis, systemic administration of hypertonic agents or prostaglandins. Freeze-fracturing and ultrastructural tracers represent the experimental probes. The precise knowledge of the anatomical mechanisms which regulate the intraocular pressure is necessary for a better understanding of the pathogenesis of glaucomas and for devising new pharmacological methods for their control. BIBLIOGRAPHIC REFERENCES: Raviola, E. and G. Raviola: Difference in internal structure of the postsynaptic membrane at ribbon and conventional synapses in the inner plexiform layer of the retina. J. Cell Biol. 67: 355 a, 1975. Raviola, G.: Blood-aqueous barrier can be circumvented by lowering intraocular pressure. Proc. Nat. Acad. Sci. U.S.A. 73: 638-642, 1976.